It seems to me that both cryptocurrencies will still dominate in the future so it's better if you put your money on both cryptocurrencies and hold them long term for good. Being on top means a very promising crypto and already been tested through times so it's just a good idea to have them both in your portfolio.
I agree with you better choose both for investment because it will be very profitable in the future, Bitcoin and Ethereum are the best coins I call these two coins as king and queen of coins so I am sure will get bigger profit if choose both.